1. Field of the Invention
The invention relates to a process for producing a chemical-resistant protective layer for a rotary body having a base body made from fiber-reinforced plastic, and to a rotary body having an interlayer and a functional layer.
2. Description of the Related Art
It is known that considerable advantages can be achieved by using fiber-reinforced plastics in mechanical engineering, automotive engineering and plant construction. These materials are more lightweight than metals and, given a suitable design, have at least equal mechanical properties, in particular when used for rapidly moving parts, such as shafts, rollers or the like.
Rapidly rotating rotary bodies or rolls of printing machines, which are produced from metal, are known to be exposed to considerable inertia forces for mass reasons, and these forces are disadvantageous in particular when the machine speeds change. Therefore, even now roll bodies made from fiber-reinforced, in particular carbon fiber-reinforced plastic, are already in use.
Without a chemical-resistant, corrosion-resistant coating, fiber-reinforced roll bodies for printing machines, such as dampening rolls, inking rolls, plate cylinders, blanket cylinders, and also for the sleeve technique, etc., can be rapidly damaged through interaction with printing auxiliaries. Examples of printing auxiliaries are inks, dampening agents, detergents and all substances which come into contact with the surfaces of the rolls.
It is fundamentally the case that any fiber-reinforced material can only retain its profile of properties if the matrix does not lose its adhesion to the fibers and there are no changes in dimensions, in the form of swelling or shrinking. In the case of fiber-reinforced plastics, for example, what is known as delamination as a result of the plastic matrix taking up water, associated with a dramatic loss of strength, is particularly feared.
It is known to coat fiber-reinforced plastics, in particular by thermal spraying, particular attention being paid to the problems of promoting adhesion (cf. for example DE 36 17 034 C2 and DE 36 08 286 A1), while the chemicals resistance of the coatings to protect the base body has hitherto been dealt with unspecifically, or has even not been dealt with at all.
DE 42 04 896 C2 has likewise disclosed coating a heat-sensitive base body made from fiber-reinforced epoxy resin by plasma spraying for a wear-resistant, chemically resistant, inorganic covering layer, or etched plastic layer, with a previously applied thermoplastic layer or etched plastic layer offering the adhesion for the adhesion promoter layer. The known extreme cooling rates of the sprayed particles during thermal spraying, of 105-106 K/s, in particular in combination with the cooling measures required for fiber-reinforced plastics, such as liquid CO2 cooling, etc., are scarcely able to achieve the desired adhesion-promoting effect whereby sprayed particles are completely incorporated in the thermoplastic layer.
In particular, EP 0 514 640 B1 also describes a process for coating fiber-reinforced plastic bodies by means of thermal spraying processes using an interlayer of synthetic resin in which ceramic particles are dispersed and which is ground down after curing, in order to offer the actual functional layer of metal or ceramic plastic-free adhesion points made from the same material. The insufficient chemicals resistance of an interlayer of synthetic resin of this type, and the fatal consequences for the fiber-reinforced plastic base body on contact with chemicals, such as for example printing auxiliaries, are not described.
The invention is therefore based on the object of producing a chemicals-resistant protective layer for fiber-reinforced plastic bodies and providing a rotary body having a base body made from fiber-reinforced plastic and a protective layer of this type, so that not only is it ensured that the base body is protected, but also a securely adhering join to a wear-resistant and corrosion-resistant functional layer above it, which is preferably to be applied by thermal spraying, is also provided.
The object on which the invention is based is achieved by first of all protecting the fiber-reinforced plastic component, i.e. the base body of a rotary body, with a layer of hard rubber or thermoplastic, in which metal or ceramic particles are dispersed in an amount of from 5% by volume-80% by volume. This layer is then ground down, and then the layer of hard rubber or thermoplastic is coated with a metal and/or ceramic layer, preferably by thermal spraying.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.